The Alcohol Regulatory and Licensing Authority is aware of other breaches by Countdown supermarkets elsewhere in the country - including offering illegally discounted alcohol as part of a national campaign - and says it is concerned at the number of recent failures.
The latest bans in Auckland were the result of controlled-purchase operations conducted by police last August, September and October.
Countdown's Sylvia Park and St Johns stores had their licences suspended for three days last week and Countdown Lynfield in Mt Roskill had its licence suspended for five days, beginning last Saturday. The managers of the three supermarkets have had their manager's certificates suspended for 30 days.
Auckland City police district operations manager Ross Barnaby said the incidents involved serving alcohol to two 17-year-old girls and a 16-year-old girl.
He said in two cases - at Countdown St John and Sylvia Park - the underage teens handed over their IDs which were checked by staff, who completed the sales anyway. This allowed a 17-year-old to purchase a $10 bottle of wine, and a 16-year-old to buy an $11.99 four pack of cider.
The Alcohol Regulatory and Licensing Authority said in a decision that the cases "would appear to indicate systemic issues" and hoped Countdown would review its systems to prevent any repeats.
A spokesman for Progressive Enterprises, which operates Countdown supermarkets, said the company accepted the authority's decision and was disappointed three stores failed a controlled purchase operation.
Following the breaches last year, the spokesman said the company introduced measures and training for staff to minimise the risk of sale of alcohol to minors.
These included a double authorisation policy for a supervisor to approve the sale of alcohol before a checkout operator can proceed with a sale and mystery shoppers testing compliance of alcohol laws.
"Progressive Enterprises serves more than 2.7 million customers a week across the country and we take our responsibilities around selling alcohol very seriously," the spokesman said.
Alcohol sale breaches
•September 2015: Three Auckland Countdown stores receive alcohol sale bans for selling booze to minors during controlled purchase operations last year.
•September 2015: Countdown's Dunedin store banned from selling alcohol for three days after offering illegally discounted alcohol in a nationwide campaign.
•April 2015: Upmarket supermarket chain Farro Fresh copped a week-long liquor licence ban at its Grey Lynn store and five days at its Mt Wellington branch following a controlled purchase operation last December.
•August 2012: Countdown Takapuna sells alcohol to a man who was demonstrably drunk. The supermarket was banned from selling alcohol for a week.